[bluewalt]

That's a relevant advice IMO.

However, as a tech guy trying to build stuff too, I need continuous motivation for this. I need to stay in a "flow" state. And a good fuel to this is to learn new cool things during the journey.

To put it differently, I think you need to find the right balance between fun and efficiency, even if your goal is to earn money in the end. Trying to always look for the maximum efficiency could be a short term vision that quickly lead to boringness.